X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Ffloat-tran.lisp;h=a1184e12ae59221f26aa7c22738b823fe6ca8253;hb=49e8403800426f37a54d9b87353a31af36e7af40;hp=681aa48868c8fd2904e340e78ff34f6db506baeb;hpb=07ab1e4811ab16f95a9a5e8d767426a0787f22c0;p=sbcl.git

diff --git a/src/compiler/float-tran.lisp b/src/compiler/float-tran.lisp
index 681aa48..a1184e1 100644
--- a/src/compiler/float-tran.lisp
+++ b/src/compiler/float-tran.lisp
@@ -15,8 +15,10 @@
 
 ;;;; coercions
 
-(defknown %single-float (real) single-float (movable foldable))
-(defknown %double-float (real) double-float (movable foldable))
+(defknown %single-float (real) single-float
+    (movable foldable))
+(defknown %double-float (real) double-float
+    (movable foldable))
 
 (deftransform float ((n f) (* single-float) *)
   '(%single-float n))
@@ -332,6 +334,68 @@
   (%deftransform x '(function (double-float single-float) *)
                  #'float-contagion-arg2))
 
+(macrolet ((def (type &rest args)
+             `(deftransform * ((x y) (,type (constant-arg (member ,@args))) *
+                               ;; Beware the SNaN!
+                               :policy (zerop float-accuracy))
+                "optimize multiplication by one"
+                (let ((y (lvar-value y)))
+                  (if (minusp y)
+                      '(%negate x)
+                      'x)))))
+  (def * single-float 1.0 -1.0)
+  (def * double-float 1.0d0 -1.0d0))
+
+;;; Return the reciprocal of X if it can be represented exactly, NIL otherwise.
+(defun maybe-exact-reciprocal (x)
+  (unless (zerop x)
+    (multiple-value-bind (significand exponent sign)
+        ;; Signals an error for NaNs and infinities.
+        (handler-case (integer-decode-float x)
+          (error () (return-from maybe-exact-reciprocal nil)))
+      (let ((expected (/ sign significand (expt 2 exponent))))
+        (let ((reciprocal (/ 1 x)))
+          (multiple-value-bind (significand exponent sign) (integer-decode-float reciprocal)
+            (when (eql expected (* sign significand (expt 2 exponent)))
+              reciprocal)))))))
+
+;;; Replace constant division by multiplication with exact reciprocal,
+;;; if one exists.
+(macrolet ((def (type)
+             `(deftransform / ((x y) (,type (constant-arg ,type)) *
+                               :node node)
+                "convert to multiplication by reciprocal"
+                (let ((n (lvar-value y)))
+                  (if (policy node (zerop float-accuracy))
+                      `(* x ,(/ n))
+                      (let ((r (maybe-exact-reciprocal n)))
+                        (if r
+                            `(* x ,r)
+                            (give-up-ir1-transform
+                             "~S does not have an exact reciprocal"
+                             n))))))))
+  (def single-float)
+  (def double-float))
+
+;;; Optimize addition and subsctraction of zero
+(macrolet ((def (op type &rest args)
+             `(deftransform ,op ((x y) (,type (constant-arg (member ,@args))) *
+                                 ;; Beware the SNaN!
+                                 :policy (zerop float-accuracy))
+                'x)))
+  ;; No signed zeros, thanks.
+  (def + single-float 0 0.0)
+  (def - single-float 0 0.0)
+  (def + double-float 0 0.0 0.0d0)
+  (def - double-float 0 0.0 0.0d0))
+
+;;; On most platforms (+ x x) is faster than (* x 2)
+(macrolet ((def (type &rest args)
+             `(deftransform * ((x y) (,type (constant-arg (member ,@args))))
+                '(+ x x))))
+  (def single-float 2 2.0)
+  (def double-float 2 2.0 2.0d0))
+
 ;;; Prevent ZEROP, PLUSP, and MINUSP from losing horribly. We can't in
 ;;; general float rational args to comparison, since Common Lisp
 ;;; semantics says we are supposed to compare as rationals, but we can
@@ -1178,27 +1242,45 @@
 ;;; of complex operation VOPs.
 (macrolet ((frob (type)
              `(progn
+                (deftransform complex ((r) (,type))
+                  '(complex r ,(coerce 0 type)))
+                (deftransform complex ((r i) (,type (and real (not ,type))))
+                  '(complex r (truly-the ,type (coerce i ',type))))
+                (deftransform complex ((r i) ((and real (not ,type)) ,type))
+                  '(complex (truly-the ,type (coerce r ',type)) i))
                ;; negation
+                #!-complex-float-vops
                (deftransform %negate ((z) ((complex ,type)) *)
                  '(complex (%negate (realpart z)) (%negate (imagpart z))))
                ;; complex addition and subtraction
+               #!-complex-float-vops
                (deftransform + ((w z) ((complex ,type) (complex ,type)) *)
                  '(complex (+ (realpart w) (realpart z))
                            (+ (imagpart w) (imagpart z))))
+               #!-complex-float-vops
                (deftransform - ((w z) ((complex ,type) (complex ,type)) *)
                  '(complex (- (realpart w) (realpart z))
                            (- (imagpart w) (imagpart z))))
                ;; Add and subtract a complex and a real.
+               #!-complex-float-vops
                (deftransform + ((w z) ((complex ,type) real) *)
-                 '(complex (+ (realpart w) z) (imagpart w)))
+                 `(complex (+ (realpart w) z)
+                           (+ (imagpart w) ,(coerce 0 ',type))))
+               #!-complex-float-vops
                (deftransform + ((z w) (real (complex ,type)) *)
-                 '(complex (+ (realpart w) z) (imagpart w)))
+                 `(complex (+ (realpart w) z)
+                           (+ (imagpart w) ,(coerce 0 ',type))))
                ;; Add and subtract a real and a complex number.
+               #!-complex-float-vops
                (deftransform - ((w z) ((complex ,type) real) *)
-                 '(complex (- (realpart w) z) (imagpart w)))
+                 `(complex (- (realpart w) z)
+                           (- (imagpart w) ,(coerce 0 ',type))))
+               #!-complex-float-vops
                (deftransform - ((z w) (real (complex ,type)) *)
-                 '(complex (- z (realpart w)) (- (imagpart w))))
+                 `(complex (- z (realpart w))
+                           (- ,(coerce 0 ',type) (imagpart w))))
                ;; Multiply and divide two complex numbers.
+               #!-complex-float-vops
                (deftransform * ((x y) ((complex ,type) (complex ,type)) *)
                  '(let* ((rx (realpart x))
                          (ix (imagpart x))
@@ -1207,39 +1289,81 @@
                     (complex (- (* rx ry) (* ix iy))
                              (+ (* rx iy) (* ix ry)))))
                (deftransform / ((x y) ((complex ,type) (complex ,type)) *)
+                 #!-complex-float-vops
                  '(let* ((rx (realpart x))
                          (ix (imagpart x))
                          (ry (realpart y))
                          (iy (imagpart y)))
                     (if (> (abs ry) (abs iy))
                         (let* ((r (/ iy ry))
-                               (dn (* ry (+ 1 (* r r)))))
+                               (dn (+ ry (* r iy))))
                           (complex (/ (+ rx (* ix r)) dn)
                                    (/ (- ix (* rx r)) dn)))
                         (let* ((r (/ ry iy))
-                               (dn (* iy (+ 1 (* r r)))))
+                               (dn (+ iy (* r ry))))
                           (complex (/ (+ (* rx r) ix) dn)
-                                   (/ (- (* ix r) rx) dn))))))
+                                   (/ (- (* ix r) rx) dn)))))
+                 #!+complex-float-vops
+                 `(let* ((cs (conjugate (sb!vm::swap-complex x)))
+                         (ry (realpart y))
+                         (iy (imagpart y)))
+                    (if (> (abs ry) (abs iy))
+                        (let* ((r (/ iy ry))
+                               (dn (+ ry (* r iy))))
+                          (/ (+ x (* cs r)) dn))
+                        (let* ((r (/ ry iy))
+                               (dn (+ iy (* r ry))))
+                          (/ (+ (* x r) cs) dn)))))
                ;; Multiply a complex by a real or vice versa.
+               #!-complex-float-vops
                (deftransform * ((w z) ((complex ,type) real) *)
                  '(complex (* (realpart w) z) (* (imagpart w) z)))
+               #!-complex-float-vops
                (deftransform * ((z w) (real (complex ,type)) *)
                  '(complex (* (realpart w) z) (* (imagpart w) z)))
-               ;; Divide a complex by a real.
+               ;; Divide a complex by a real or vice versa.
+               #!-complex-float-vops
                (deftransform / ((w z) ((complex ,type) real) *)
                  '(complex (/ (realpart w) z) (/ (imagpart w) z)))
+               (deftransform / ((x y) (,type (complex ,type)) *)
+                 #!-complex-float-vops
+                 '(let* ((ry (realpart y))
+                         (iy (imagpart y)))
+                    (if (> (abs ry) (abs iy))
+                        (let* ((r (/ iy ry))
+                               (dn (+ ry (* r iy))))
+                          (complex (/ x dn)
+                                   (/ (- (* x r)) dn)))
+                        (let* ((r (/ ry iy))
+                               (dn (+ iy (* r ry))))
+                          (complex (/ (* x r) dn)
+                                   (/ (- x) dn)))))
+                 #!+complex-float-vops
+                 '(let* ((ry (realpart y))
+                         (iy (imagpart y)))
+                   (if (> (abs ry) (abs iy))
+                       (let* ((r (/ iy ry))
+                              (dn (+ ry (* r iy))))
+                         (/ (complex x (- (* x r))) dn))
+                       (let* ((r (/ ry iy))
+                              (dn (+ iy (* r ry))))
+                         (/ (complex (* x r) (- x)) dn)))))
                ;; conjugate of complex number
+               #!-complex-float-vops
                (deftransform conjugate ((z) ((complex ,type)) *)
                  '(complex (realpart z) (- (imagpart z))))
                ;; CIS
                (deftransform cis ((z) ((,type)) *)
                  '(complex (cos z) (sin z)))
                ;; comparison
+               #!-complex-float-vops
                (deftransform = ((w z) ((complex ,type) (complex ,type)) *)
                  '(and (= (realpart w) (realpart z))
                        (= (imagpart w) (imagpart z))))
+               #!-complex-float-vops
                (deftransform = ((w z) ((complex ,type) real) *)
                  '(and (= (realpart w) z) (zerop (imagpart w))))
+               #!-complex-float-vops
                (deftransform = ((w z) (real (complex ,type)) *)
                  '(and (= (realpart z) w) (zerop (imagpart z)))))))
 
@@ -1370,15 +1494,48 @@
   (define-frobs truncate %unary-truncate)
   (define-frobs round %unary-round))
 
-;;; Convert (TRUNCATE x y) to the obvious implementation.  We only want
-;;; this when under certain conditions and let the generic TRUNCATE
-;;; handle the rest.  (Note: if Y = 1, the divide and multiply by Y
-;;; should be removed by other DEFTRANSFORMs.)
-(deftransform truncate ((x &optional y)
-                        (float &optional (or float integer)))
-  (let ((defaulted-y (if y 'y 1)))
-    `(let ((res (%unary-truncate (/ x ,defaulted-y))))
-       (values res (- x (* ,defaulted-y res))))))
+(deftransform %unary-truncate ((x) (single-float))
+  `(%unary-truncate/single-float x))
+(deftransform %unary-truncate ((x) (double-float))
+  `(%unary-truncate/double-float x))
+
+;;; Convert (TRUNCATE x y) to the obvious implementation.
+;;;
+;;; ...plus hair: Insert explicit coercions to appropriate float types: Python
+;;; is reluctant it generate explicit integer->float coercions due to
+;;; precision issues (see SAFE-SINGLE-COERCION-P &co), but this is not an
+;;; issue here as there is no DERIVE-TYPE optimizer on specialized versions of
+;;; %UNARY-TRUNCATE, so the derived type of TRUNCATE remains the best we can
+;;; do here -- which is fine. Also take care not to add unnecassary division
+;;; or multiplication by 1, since we are not able to always eliminate them,
+;;; depending on FLOAT-ACCURACY. Finally, leave out the secondary value when
+;;; we know it is unused: COERCE is not flushable.
+(macrolet ((def (type other-float-arg-types)
+             (let ((unary (symbolicate "%UNARY-TRUNCATE/" type))
+                   (coerce (symbolicate "%" type)))
+               `(deftransform truncate ((x &optional y)
+                                        (,type
+                                         &optional (or ,type ,@other-float-arg-types integer))
+                                        * :result result)
+                  (let ((result-type (lvar-derived-type result)))
+                    (if (or (not y)
+                            (and (constant-lvar-p y) (= 1 (lvar-value y))))
+                        (if (values-type-p result-type)
+                            `(let ((res (,',unary x)))
+                               (values res (- x (,',coerce res))))
+                            `(let ((res (,',unary x)))
+                               ;; Dummy secondary value!
+                               (values res x)))
+                        (if (values-type-p result-type)
+                            `(let* ((f (,',coerce y))
+                                    (res (,',unary (/ x f))))
+                               (values res (- x (* f (,',coerce res)))))
+                            `(let* ((f (,',coerce y))
+                                    (res (,',unary (/ x f))))
+                               ;; Dummy secondary value!
+                               (values res x)))))))))
+  (def single-float ())
+  (def double-float (single-float)))
 
 (deftransform floor ((number &optional divisor)
                      (float &optional (or integer float)))